How to make the surface look smooth, i have used the modifiers
I have taken a sphere and added Subdivision Surface Modifier to it with the view 2 and Render 0



As you can see the sphere look smooth. But when i hit render i get this render



Flat or un-smooth sphere

Reason is the setting in the subdivision instead of Render value 0 make the same value of 2

And you will see the same result seen in the 3d solid view.